1. Field
The present invention relates to a dispersion liquid for electrophoretic display, a display medium, and a display device.
2. Description of the Related Art
There has been proposed a display device where a dispersion liquid prepared by dispersing two or more kinds of particles differing in the charging characteristics and color in a dispersion medium is disposed between a pair of electrodes arranged to face each other and a display is performed by applying a voltage between the electrodes and thereby moving a part of the particles in the dispersion liquid.
For example, JP-A-2001-188269 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses a liquid for electrophoretic display, including a liquid medium containing (A) one or more kinds of colored particles differing in the color tone and (B) one or more kinds of colored particles differing in the color tone, wherein the colored particle (A) contains (A) a colored particle capable of moving in the dispersion medium in correspondence to a given electric field applied from outside and (B) a colored particle incapable of moving in the dispersion medium when a given electric field is applied from outside.
JP-A-2002-338642 discloses an image display medium containing a dispersion liquid between two electrically conductive layers disposed with a desired spacing, at least one or both of which are light-transmitting, the dispersion liquid being composed of a silicone oil solvent and a white or colored particle having an acidic group at least on the surface but not having a basic group.
JP-A-2005-128141 discloses an electrophoretic display medium including an electrically insulating carrier liquid having dispersed therein at least one or more kinds of electrophoretic particles, wherein the electrically insulating carrier liquid contains a specific silicone-based compound.
JP-A-2005-140835 discloses a dispersion liquid for electrophoretic display, containing a solvent, a pigment and a dispersant, wherein the dispersant is a block copolymer composed of block A having hydrophilicity and block B having hydrophobicity.
JP-A-2009-134010 discloses a particle dispersion liquid having dispersed therein a particle group capable of moving according to an electric field, in which the particle dispersion liquid contains a carboxyl-modified silicone oil and a first solvent containing at least either one of a silicone oil and a paraffin-based hydrocarbon solvent.